Add no snapshots error page

If there are no snapshots yet the scheduler page would throw an error.
Hence, I have add an error page to deal with this case.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Write specification for repository import

The repository import is now tested by a test file. Additionally, I have
added the database_cleaner gem establishing an interface to clean/reset
the database before/after each specification is executed.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Add factory girl gem to write snapshot import test

Finally, I have introduced the factory girl gem to the project. I am
starting to use it for the unit test covering the snapshot import.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Add test case for the statistic compilation

The statistic compilation is now covered, too. Although this is more
like a dummy test, since the test snapshot does not contain any
resources. So it is likely that this test is updated in the future.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Refactor snapshot importer to use Oj parser

The snapshot importer uses now the Oj parser. It blends in very well.
Since I changed the dump format to JSON delimited lines I do not have
to worry about an eventful parser implementation. I just read the files
line by line and parse each one.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>